1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a vehicle and a control method thereof, and more particularly to a vehicle including an internal combustion engine, a stepped transmission that has an input shaft connected to an output shaft of the internal combustion engine and the output shaft connected to an axle side, wherein the stepped transmission is capable of speed-changing power input to the input shaft while changing shift speed and outputting the speed-changed power to the output shaft, and a control unit that controls the internal combustion engine and the stepped transmission such that the vehicle is caused to travel in accordance with power based on an output request from an operator, and a control method for the vehicle.
2. Description of the Related Art
A vehicle having an automatic transmission that is driven by a hydraulic control device that changes the speed of power from an engine and outputs the speed-changed power has been proposed in the related art (see, for example, Japanese Patent Application Publication No. JP-A-2004-36673).
Incidentally, when the related art transmission enters a neutral state due to an abnormality in the hydraulic control device, racing occurs in an input shaft of the transmission due to torque from the engine, and therefore an abnormality in the transmission can be determined by comparing a ratio between the rotation speed on the output side of the transmission and the rotation speed on the input side using a subject reduction ratio. To prevent erroneous determinations, the existence of an abnormality in the transmission is usually confirmed when rotation of the input shaft continues for a predetermined time period or longer, but depending on the degree of rotation in the input shaft, a rotary body (a planetary gear mechanism) of the transmission may over-rotate beyond its tolerance. A durable rotary body may be provided in response to such cases, but this results in increased weight and the overall size of the transmission.